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iOS Build a Blog Reader iPhone App Getting Data from the Web Mutable vs Immutable

Posted by Faizan Mohammed
Faizan Mohammed
2,036 Points

Not able to get through the challenge.

What's wrong in my code?

mutablearray.mm 
NSMutableArray *elements=[NSMutableArray array];
[elements addObject:@"Helium"];
[elements addObject:@"Neon"];
[elements addObject:@"Argon"];
[elements removeObject:@"Neon"];
[elements removeObjectAtIndex:2];

4 Answers

Faizan Mohammed
Faizan Mohammed
2,036 Points
Faizan Mohammed
Faizan Mohammed
2,036 Points

Got the answer. The syntax is [elements removeLastObject]; . Thank you guys for the help.

James Rowe
James Rowe
2,551 Points

Ahhhhh thank you!!

eirikvaa
eirikvaa
18,015 Points
eirikvaa
eirikvaa
18,015 Points

You only have two objects in your array (after deleting "Neon"), and are trying to delete object number three, which doesn't exist. Remember that the index starts at 0 in an array, so index 2 would be the third object.

Kyle Pontius
Kyle Pontius
6,190 Points

I agree with Eirik, you're accessing an index that has been deleted. At the point that the final line executes, you should only have 0 and 1 as available indices.

Faizan Mohammed
Faizan Mohammed
2,036 Points
Faizan Mohammed
Faizan Mohammed
2,036 Points

I have changed it to [elements removeObjectAtIndex:1] and even then it does not work . it says a method must be called on the "elements" array to remove the last object.

Faizan Mohammed
Faizan Mohammed
2,036 Points
Faizan Mohammed
Faizan Mohammed
2,036 Points

The new code is NSMutableArray *elements=[NSMutableArray array]; [elements addObject:@"Helium"]; [elements addObject:@"Neon"]; [elements addObject:@"Argon"]; [elements removeObject:@"Neon"]; [elements removeObjectAtIndex:1];